The present invention relates to a water-permeable adhesive tape for processing semiconductor wafers and/or semiconductor related materials. More particularly, the present invention is concerned with a water-permeable adhesive tape which can be used to fix a semiconductor wafer when cutting and separating the semiconductor wafer into IC element chips.
Conventionally, semiconductor wafers and semiconductor related materials are separated into chips and IC parts by cutting the wafers or the material with a rotary diamond blade which is also known as a dicing blade. Semiconductor related materials as described in the present invention include a BGA package, printed circuits, ceramic boards and glass parts for liquid crystal equipment. In the aforementioned method, the semiconductor wafers and semiconductor related materials are cut into IC element chips by means of diamond particles in the blade. In order to fix the semiconductor wafer or semiconductor related material during this dicing process, the semiconductor wafer or semiconductor related material is usually bonded to an adhesive tape which is also known as a dicing tape. After the semiconductor wafer or semiconductor related material has been cut into IC element chips, the IC element chips can be picked up from the adhesive tape. The adhesive tape used for such a process possesses generally a layer made up of a synthetic resin, e.g. PVC, which is adhered to the wafer by means of an adhesive layer.
Recently, one drawback of this method has evolved in that cracking, chipping or defects of the IC chips and parts which are cut by this method have become a major problem resulting in poor quality of the chips and parts and a reduced productivity of this cutting method. This problem has developed as a result of down-sizing electronic equipment and the growing demand to provide wafers having a more and more reduced thickness. However, as the thickness of the semiconductor materials decreases, the tendency of this material to crack upon dicing increases. Also, some hardly separated and, thus, more brittle and harder semiconductor related materials have appeared which are more susceptible to chipping. The principle cause of this cracking or chipping problem is the cutting mechanism of the rotary diamond blade.
In order to overcome this problem, other cutting techniques have become the focus of attention and in particular laser technology appears to be advantageous since dicing using a laser beam is much more accurate and this accuracy is not greatly influenced by the thickness of the material which is to be cut. Specifically, a laser technology which may be useful for the above purpose has been described in WO 95/32834 and discloses the use of a laser beam to process material by cutting, drilling, welding, marking and material stripping whereby the laser beam is guided by a liquid jet. Specifically, a laser beam which is guided by a water stream is used to process various materials. However, one problem which may occur during the separation process using this laser technology is that chips and IC parts can delaminate from an adhesive tape bonded thereto. Due to the high pressure applied to the adhesive surface by, e.g. the water stream, these chips and IC parts cannot be fixed perfectly on the adhesive tape. Conventional adhesive tapes for processing semiconductor wafers and semiconductor related materials are therefore not suitable for laser dicing technology since chips and IC parts may fly off from the wafer or material during the dicing step or may be destructed by contamination with molten particles from the dicing.